As known, irrigation hoses, in particular flexible ones, generally comprise one or more overlapped tubular layers made from polymeric material between which one or more reinforcing layers are usually arranged.
The configuration of the reinforcement layer varies as a function of the mechanical characteristics that it is wished to give the hose, like, for example, resistance to pressure or to bursting, flexibility and ability to avoid the “kinking” phenomena, i.e. the squashing of the hose when it is subjected to twisting that causes the formation of localized choking.
The most common types of reinforcement are net-type reinforcements, in which the yarns are overlapped to form a mesh, and meshed-type reinforcement, in which the yarns are worked together to form mesh in a chain, also known as “fricae”-type mesh.
This second type of reinforcement, although it is relatively expensive and has poorer performance in terms of resistance to pressure, is generally preferred to net-type reinforcement since it makes it possible to have hoses with high malleability, i.e. high resistance to kinking.
Therefore, hoses with meshed reinforcement are particularly suitable for being used as irrigation hoses, particularly for use at home or as a hobby.
In the case in which it is necessary to give the hose both high malleability and high resistance to bursting, many overlapped reinforcement layers are used.
For example, EP 1156252 discloses an irrigation hose having two overlapped meshed reinforcement layers, separated by an intermediate layer of polyurethane foam. This solution, although it allows greater resistance to bursting, has low flexibility and is difficult to produce, in particular due to the need to arrange the two meshed layers in two distinct steps.
EP0794377 also discloses a gardening hose in which the reinforcement is formed from a first meshed layer and from a second coiled layer overlapped to the first.
Such a solution has also not proven to be satisfactory due to an increase in resistance to bursting that is not proportional to the amount of fibers inserted with respect to the single meshed layer and to a reduction in malleability, as well as to obvious difficulties in production.
FR 2849148, on the other hand, discloses a flexible gardening hose comprising a reinforcement consisting of a first meshed layer with tricot type mesh interlaced with a second layer, also meshed with mesh of the same type.
The two layers are formed from distinct and identical series of yarns, formed from the same type of fibers, so as to obtain two layers having the same number of meshes arranged on coils with the same pitch and inclination.
Moreover, every mesh belonging to one of the layers is linked with a pair of meshes of the other layer, so as to define a reinforcement defined by two distinct but mutually bound layers.
Such a solution gives the hose high resistance to pressures, at the same time maintaining high malleability.
However, a solution of this type does not bring appreciable variations to resistance to bursting of the hose, which is only slightly increased with respect to normal double layer reinforcement hoses, thus in a not very efficient manner with respect to the greater overall weight of the reinforcement layer and the higher material costs.
Irrigation hoses are also known in which the yarns of the reinforcement layer are formed from fibers with high toughness or in any case greater toughness with respect to that of polyester fiber, which represents the most commonly used fiber.
For example, US 2001/39972 discloses an irrigation hose comprising a first coiled reinforcement layer and a second meshed layer overlapped to the first. In a possible configuration thereof, one of the 20 layers is made entirely from Kevlar®.
The use of a reinforcement material with high mechanical resistance characteristics considerably increases the manufacturing costs of the hose, making it disadvantageous to use these configurations for commonly-used and relatively low-cost flexible irrigation hoses.